What Are Microbubbles?

July 2020


Microbubbles are small, gas-filled bubbles with applications throughout the life sciences, medicine, and other industries.

At Akadeum, we take microbubbles to a new level: Revolutionizing cell separation technology.

Akadeum’s buoyancy-activated cell sorting (BACS™) microbubbles are a polydisperse mixture of hollow glass microspheres used to isolate cells in a biological sample. These microbubbles capture target cells and quickly float them to the surface for removal.

Our microbubble technology is efficient, gentle, fast, and effective—all without requiring additional equipment.

Interested? Let’s take a closer look.

What Are Microbubbles Made Of?

A lot of people think our buoyancy-activated microbubbles are purely made of gas. (It makes sense: Gas bubbles are the type most familiar to many of us.) However, simple gas bubbles are not the type we use to separate cells.

Microbubbles exist in many different sizes and material compositions. While the core is usually made of gas, the microbubbles are often surrounded by a type of a shell that can be made from a variety of materials, such as polymers, lipids, or proteins.

Akadeum’s microbubbles are made of thin shells of glass with a gaseous core. These glass shells are approximately 0.7 μm thick, while the microbubbles have an average diameter of 16–18 μm.

We use glass-shelled microbubbles for a couple of reasons:

  • Density: With a density of around 0.6 g/cm3, our microbubbles have a sufficient force to lift several cells and act as an effective cell separation method.
  • Stability: A glass shell provides a stable structure so the microbubble does not easily pop.

These glass microbubbles are then coated with either streptavidin or antibodies to target cells.

How Big Are Microbubbles?

Microbubbles range in size from the nanometer length scale to micrometers. The choice in size has a lot to do with the application. For cell separation, it is important that the microbubbles are in something of a Goldilocks Zone, where they can float with a cell attached but don’t float too quickly.

At Akadeum, we have developed microbubbles that are fine-tuned for cell separation. Our polydisperse microbubbles are 16–18 μm in diameter.

With this size, there is enough buoyant force to easily float cells to the top of a fluid sample. Then, once the cells are at the top of the fluid, the cell-microbubble complexes can be removed and isolated.

How Does Microbubble Technology Work?

Microbubbles are small but mighty, able to lift targeted cells to the top of a biological sample and leave non-targeted cells behind.

The first part of the process is mixing the microbubbles with the cell sample, which overcomes the buoyant nature of the microbubbles. By slowly and gently stirring the mixture, the microbubbles have time to identify and bind to targeted cells.

Then, after capturing the targeted cells, the microbubbles float to the top of the sample, carrying the targeted cells along with them and leaving behind unwanted cells. Microbubbles can also be used in conjunction with cell centrifugation. The mixture of microbubbles and cell sample is centrifuged to accelerate the flotation of the microbubbles and pellet the non-targeted cells.

Finally, the microbubbles—and the targeted cells attached to them—are removed from the top of the sample, typically by aspiration.

Why Use Microbubble Technology?

There are many advantages to Akadeum’s BACS™ microbubble technology. Here are some highlights.

No Additional Equipment Needed

Microbubbles require no special tools, lab equipment, or consumables to separate cells. No magnet or column? No problem.

Use Any Container

Due to its buoyancy-activated properties, our microbubble technology can be used in any container. Are you working with bioreactors or large volume containers? Well, with our isolation technology, you don’t have to move the sample to other system to perform the separation. Size isn’t an issue.

Microbubbles Applied Equally Throughout Sample

Some cell isolation methods require cells to be in a specific location. In immunomagnetic methods, for example, the sample must be aligned with the magnetic field.

That’s not the case with microbubbles.

The force of buoyancy is applied equally throughout the fluid sample, so microbubbles bind to targeted cells wherever they are, leaving unwanted cells behind to settle or be pelleted to the bottom of the container.

Save Time and Shorten Workflows

Akadeum’s microbubble technology is fast and easy to use. The entire process occurs in a standard laboratory tube, taking approximately 10 minutes from start to finish. And, without the need for highly trained operators or special equipment, workflows are simplified, too.

Size Advantage

Microbubbles and mammalian cells are about the same size, which gives them a key advantage: There is a lower chance of the microbubbles interfering with non-targeted biological cells.

Are Microbubbles a Good Fit for My Project?

If you are searching for a way to improve the quality and viability of sorted cells while dramatically saving time and reducing costs, look no further than Akadeum’s buoyancy-activated microbubble technology.

Contact us with questions, and try our products today.

Back to Top